It would be hard to do with super glue, especially for a lay person. The two sides would need to be cleaned up well and then held immobile while the glue is applied and sets. I believe there would be a chance that an inexperienced person might actually glue the upper jaw to the lower one so that the tortoise couldn't open its mouth at all.
My turtle has a cracked lower jaw and can't eat by itself – looking for help and advice